[PATCH 3.12 41/62] parisc: fix mmap(MAP_FIXED|MAP_SHARED) to already mmapped address

Greg Kroah-Hartman
2013-12-10T08:02:20Z

From: Helge Deller <deller@gmx.de>

commit 0576da2c08e3d332f1b0653030d28ab804585ab6 upstream.

locale-gen on Debian showed a strange problem on parisc:
mmap2(NULL, 536870912, PROT_NONE, MAP_SHARED, 3, 0) = 0x42a54000
mmap2(0x42a54000, 103860, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 3, 0) = -1 EINVAL (Invalid argument)

Basically it was just trying to re-mmap() a file at the same address
which it was given by a previous mmap() call. But this remapping failed
with EINVAL.

The problem is, that when MAP_FIXED and MAP_SHARED flags were used, we didn't
included the mapping-based offset when we verified the alignment of the given
fixed address against the offset which we calculated it in the previous call.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/parisc/kernel/sys_parisc.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)

--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -61,8 +61,15 @@ static int get_offset(struct address_spa
return (unsigned long) mapping >> 8;
}

-static unsigned long get_shared_area(struct address_space *mapping,
- unsigned long addr, unsigned long len, unsigned long pgoff)
+static unsigned long shared_align_offset(struct file *filp, unsigned long pgoff)
+{
+ struct address_space *mapping = filp ? filp->f_mapping : NULL;
+
+ return (get_offset(mapping) + pgoff) << PAGE_SHIFT;
+}
+
+static unsigned long get_shared_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff)
{
struct vm_unmapped_area_info info;

@@ -71,7 +78,7 @@ static unsigned long get_shared_area(str
info.low_limit = PAGE_ALIGN(addr);
info.high_limit = TASK_SIZE;
info.align_mask = PAGE_MASK & (SHMLBA - 1);
- info.align_offset = (get_offset(mapping) + pgoff) << PAGE_SHIFT;
+ info.align_offset = shared_align_offset(filp, pgoff);
return vm_unmapped_area(&info);
}

@@ -82,20 +89,18 @@ unsigned long arch_get_unmapped_area(str
return -ENOMEM;
if (flags & MAP_FIXED) {
if ((flags & MAP_SHARED) &&
- (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
+ (addr - shared_align_offset(filp, pgoff)) & (SHMLBA - 1))
return -EINVAL;
return addr;
}
if (!addr)
addr = TASK_UNMAPPED_BASE;

- if (filp) {
- addr = get_shared_area(filp->f_mapping, addr, len, pgoff);
- } else if(flags & MAP_SHARED) {
- addr = get_shared_area(NULL, addr, len, pgoff);
- } else {
+ if (filp || (flags & MAP_SHARED))
+ addr = get_shared_area(filp, addr, len, pgoff);
+ else
addr = get_unshared_area(addr, len);
- }
+
return addr;
}